#scrollTop {
    width: 100%;
    height: 44px;
    background-color: #333333;
    display: none;
    position: fixed;
    top: 0;
    z-index: 2000;
}

#scrollTop>.content {
    display: flex;
    align-items: center;
    justify-content: space-between;
    width: 1200px;
    height: 44px;
    margin: auto;
    /* border: 1px solid red; */
}

.height {
    width: 100%;
    border: 1px solid red;
    height: 5000px;
}